The present invention relates to a manipulator of flat sheet of any material, in particular sheet metal plate.
Manipulators are widely used in different forms in machine tools, wherein the piece being machined must in succession assume different positions in the machine itself.
Since such manipulators must exert strong accelerations to the piece being machined, their grasping organs have the form and function of clamps or pincers, capable of firmly holding the piece itself. In the case of manipulators of flat sheet, the clamps grasp the sheets in the proximity of one of their edges.
Manipulators of flat sheet are known having one or two orthogonal axes, along each of which their grasping organs are capable of accomplishing a stroke equal to the maximum stroke which the sheet must perform along that axis or to accomplish a shorter stroke along the axis which is parallel to the grasped edge and, when necessary, to execute a "repositioning", that is, temporarily abandoning the sheet, returning along that axis and regrasping the sheet and then moving forward with it again.
However, if the sheet is large or if long strokes must be accomplished, the manipulator must be of a large size, or it must execute one or more successive repositionings: in the first case it is expensive, heavy, bulky, slow and not very rigid; in the second case, time and accuracy are lost in the opening of the clamp (or clamps), in the return strokes and in reclosing the clamps.